Another round of fighting broke out over the weekend between Israel and militants in the Gaza Strip. It was the usual thing, only more so: Until Sunday morning, only militants were reported killed on the Palestinian side. And on the Israeli side, no one was even badly hurt, except for a Thai farmworker who had the misfortune of toiling in a field outside the remarkable umbrella known as Iron Dome, the anti-missile batteries that are transforming how Israelis respond to the sound of air raid sirens.

Instead of the stark terror provoked by that rising, sickening wail, a kind of grateful curiosity has joined apprehension in the cities of southern Israel that lie within rocket range of Gaza. Iron Dome works something like miracles. Stationed outside, say, Be’er Sheva, 22 miles from Gaza, the system reads the arc of incoming missiles to determine which may threaten populated areas. Militants fired some 120 missiles since Friday. Iron Dome judged that about two-thirds of those would land far from populated areas, and simply left them alone. Of the 37 that it calculated posed a significant danger to people, the system launched interceptor rockets that, in 32 cases, met the incoming missile and exploded it in mid-air. That’s an 86 percent success rate.

On the ground, the relief was palpable.

“If you ask me, that’s the real issue, the psychological,” says Meir Elran, who runs the Homeland Security program at the Institute for National Security Studies, a Tel Aviv think tank.

Missiles are what Israelis fear most. Their powerful army, far-reaching intelligence services and officially undeclared nuclear arsenal protect them against almost every other threat. But until Iron Dome there was only scant defense against rockets fired from Gaza, the Palestinian enclave under militant control, or from Lebanon, where Hizballah fired thousands of rockets into Israel in the Second Lebanon War of 2006 — and is believed to have stockpiled some 40,000 since.

How many of those, if any, would be fired if Israel attacked Iran is a critical question. Hizballah is routinely regarded as the proxy of its creator, Iran, though no one knows if it would obey an order to retaliate for an Israeli attack on Iran’s nuclear facilities. Hamas, which also has been supported by Iran, recently said it would not be drawn in. (Its ties with Iran, always looser, lately have frayed badly over Iran’s support for Syrian leader Bashar Assad.)

The sterling initial performance of Iron Dome would at least appear to make calculations about retaliation a bit less fraught, and might therefore make an Israeli strike on Iran marginally more likely. The safer the Israeli public feels from missiles, the thinking goes, the greater the leeway for its leadership to decide upon an action that risks blowback. As Elran put it: “The more we are protected, the free-er we are.” Indeed that was the logic behind the eleventh-hour postponement of Austere Challenge, the joint military exercise that would have brought U.S. Patriot and possibly other anti-missile systems to Israel this spring. Washington postponed the deployment in January, when the drumbeat to war was growing uncomfortably loud, and the immediate prospect of sending American troops and anti-missile batteries to Israel looked entirely too much like something that encouraged the possibility of an Israeli strike on Iran – something that had occurred to some Israeli military officials as well.

Experts caution, however, that the skies are not nearly so clear as they seem. Israel has only three Iron Dome batteries, enough only to protect the cities closest to Gaza (Ashkelon, Ashdod and Be’er Sheva). At least three times as many would be needed to shield other population centers, and even with a special grant from Washington only three more are in the pipeline, for a total of six.

Nor is Israel’s umbrella against medium-range missiles yet on line. That system, known both as Magic Wand and David’s Sling, is due to deploy in about a year. It would aim to stop missiles fired from beyond about 50 miles, the outer range of Iron Dome. A third system, dubbed Arrow and already in operation, is designed to intercept ballistic missiles such as Iran’s Shahab-3.

“Magic Wand would be a great help, but it would not be enough,” says Yiftah Shapir, a retired Air Force intelligence officer at INSS. “No amount of defense is ever enough. Some rockets always get through.”

That they do. The last Israeli civilian killed by one had gone outside to see Iron Dome knock down the missile that slipped through the system and exploded on his street, killing him.

“Everybody still has to be in shelters,” notes Shapir. “The damage to the economy is just the same. Even if you have an Iron Dome protecting every town in Israel, children would not go to school. Their parents would not go to work. This is a major problem.”

Nor is it clear how well Iron Dome would perform in genuinely warlike conditions – that is, with missile barrages not in the dozens, but in the hundreds or even thousands. Elran warns that, however reassuring its performance over the weekend, the system still must be regarded as untested: “You can’t really make an extrapolation from what’s happened in the last 36 hours,” he says.

Such a test does not appear imminent. In Gaza, the missiles so far have been launched not by Hamas, which has thousands in its stocks, but rather by rival militant groups such as Islamic Jihad and the Popular Resistance Committees. The weekend’s tit-for-tat began after Israel rocketed a car carrying the head of the PRC, who the Israeli military claims had been planning another attack similar to the August 2011 ambush outside Eilat, the Israeli Red Sea resort city. The group responded with what rockets it had, and other smaller groups joined in. Israeli forces responded each time, killing 15 militants and, on Sunday morning, a 12-year-old boy.